It's as Slasher said.
After a typical N-1 you would want maximum gradient/angle. Which you will achieve at V2+ a bit (typically 10 to 20). (remember improved climb where V2 itself is increased to increase gradient and thus the climb limited TOW).
If the engine failure occurs when flying V2+10 you will have a better climb gradient than at just V2. In general it is accepted that maintaining V2+10 will give you a better overall climb gradient even though you could exchange the 10kts excess speed for some temporary increase of gradient, which would be perfectly as per the performance numbers btw.
If the engine failure occurs at V2 or below you would obviously not accelerate to V2+10 (or so) because your performance numbers do not cater for this acceleration.